IBM 7220, Instruction Manual

Page: 136 / 155

E-12
Appendix E, ALPHABETICAL LISTING OF COMMANDS
\N n Address command
When the 7220 is daisy-chained with other compatible instruments this command will
change which instrument is addressed. All daisy-chained instruments receive
commands but only the currently addressed instrument will implement or respond to
the commands. The exception is the \N n command. If n matches the address set from
the front panel the instrument will switch into addressed mode. If n does not match
the address set from the front panel the instrument will switch into unaddressed mode.
Note: The \N n command does not change the address of an instrument but which
instrument is addressed.
Warning: All instruments must have a unique address.
N Report overload byte
Causes the lock-in amplifier to respond with the overload byte.
Bit 0 not used
Bit 1 CH1 output overload (> ±120 %FS)
Bit 2 CH2 output overload (> ±120 %FS)
Bit 3 Y output overload (> ±300 %FS)
Bit 4 X output overload (> ±300 %FS)
Bit 5 not used
Bit 6 input overload
Bit 7 reference unlock
NC New curve
Initializes the curve storage memory and status variables. All record of previously
taken curves is removed.
NHZ.
Causes the lock-in amplifier to respond with the square root of the noise spectral
density measured at the Y output, expressed in volt/
√
Hz or amp/
√
Hz referred to the
input. This measurement assumes that the Y output is Gaussian with zero mean.
(Section 3.10). The command is only available in floating point mode.
This command is not available when the reference frequency exceeds 60 kHz.
NN[.] Noise output
In fixed point mode causes the lock-in amplifier to respond with the mean absolute
value of the Y output in the range 0 to 12000, full-scale being 10000. If the mean
value of the Y output is zero, this is a measure of the output noise.
In floating point mode causes the lock-in amplifier to respond in volts.